Heisenberg group

Etymology
Named after.

Proper noun
1 & a & c\\ 0 & 1 & b\\ 0 & 0 & 1\\ \end{pmatrix}$$ under the operation of matrix multiplication, arising in the description of one-dimensional quantum-mechanical systems.
 * 1)  The group of 3&times;3 upper triangular matrices of the form $$\begin{pmatrix}